Electric discharge device



Aug. 11, 1936.

s. P. SASHOFF 2,050,383 v ELECTRIC DISCHARGE DEVICE Filed Deo. 4, 1931 E:j [WJ/i5 j? Z 7 l 7 f f ff j f5 4f l f5 g 2./ o 3 s /7 o f7 RZ! 2f 2f lu ogg goo 55 o 5 y 3 f i 7 f, ..251 f3/O '5 l n. ,if 'EL f z5 55wiwi-:555s: INVENTOR /vaf/? 5&50/j4 ig and BY Patented Aug. 11, 1936UNITED STATES 2,050,383 f ELECTRIC DISCHARGE DEVICE Stephan P. Sashoff,Swissvale, Pa., assigner to Westinghouse Electric & ManufacturingCompany, a corporation of Pennsylvania Application December 4, 1931,Serial No."578,904

9 Claims.

My invention relates to electric discharge devices and has particularrelation to gaseous electric discharge devices of a type havingsymmetricelectrical properties.

It is an object of my invention to provide a gaseous electricv dischargedevice having the property of symmetric conductivity and capable ofaccurate control. 5

Another object of my invention is to provide for a gaseous electricdischarge device of the type capable of symmetric conductivity, acontrol electrode of such geometric structure that it shall completelyprevent the transmission of a current in the device unless it is giventhe proper potential relative to the princip-al electrodes thereof. v

Still another object of my invention is to provide an electric dischargedevice having the property of symmetric conductivity and capable ofconducting substantially identical wave forms in both directions. 1

A further object of my invention is to provide an electric dischargedevice, of the type having the property of symmetric conductivity andincorporating a control electrode, that shall yield a substantiallysymmetric electrical output.A

vMore concisely stated, it is an object of my invention to provide anelectric discharge device incorporting a control electrode and havingthe pro-perty of symmetric electrical conductivity, such that thecontrol electrode shall always regulate the activity of the device andthe current transmitted by the device' shall-have the proper symmetricproperties. 1 I

In experimenting with gaseous electric dikscharge devices of the typehaving the property of symmetric conductivity, I have Afound that unlessthe elements of the principal electrodes of a gaseous device aresubstantially completely shielded from eachother by the controlelectrode, the device has a tendency to become energized by reason ofthe fact that an ionization current iiows between the Aelements of theprin- 'cipal electrodes'that are exposed to each other. I havetherefore, providedv an electric discharge device comprising a pluralityof principal emitting electrodesr preferably of the hot-cathode type,and a control electrode of such structure that it completely shields theprincipal electrodes from Leach other. Y

The principal electrodes normally comprise a plurality of filamentssuitably supported on a plurality of conducting rods through which theheating energy is fed tothe laments. The control electrode is an openstructure preferably of `larlty in the appended claims.

(Cl. Z50- 27) cylindrical form. The base of the cylinder is disposedbetween the electrodes, while the walls of the cylinder enclose one ofthe electrodes and its supporting structure. Byv reason of theshieldingprovided by the structure of the con- 5 trol electrode,emission is prevented through the gaseous medium between the elementsyof the supporting structure'of the principal electrodes.

In experimenting with the tube of the structure described hereinabove, Ihave found'that 10 vfor many Ypurposes it isl completely suitable.

sible. In such a case, the control electrode should `preferably bear thesame relation to one principal electrode as it does tothe other.

In a modification of my device particularly 25 adaptable to symmetricconductivity, I have found that the control electrode shouldpreferably'be in the form of a hollow cylinder divided into two sectionsby a central partition. The cylinder is disposed with its Walls adjacentand 30 parallel to the supporting structure of the prin- 'cipalelectrodes, and with the partition parallel to the emitting filamentsrof the electrodes.

It is moreover well to keep in mind that when `complete symmetricconductivity isfdesired, the 35 inputk and the output circuitsassociated with the device should be as nearly symmetric Yas possible.The novel features that I consider characteristic of my invention areset forth with particu- The invention 40 itself, however, both as toitsorganization and its method of operation, together with additionalobjects and advantages thereof, will best be understood from thefollowing description of specinc embodiments when read in connectionwith 45 the accompanying drawing, in which:

'The apparatus shown in'Fig. 1 comprises a container lpreferablycomposed of non-conducting '55 material such as glass, andequipped with a plurality of re-entrant stems 3 and 5 and a plurality ofpresses 1 and 9, integral with the stems. A plurality of leads I I andI3 of comparatively heavy structure project through each of the presses1 and 9 and are so welded thereto that the leakage of air into thecontainer I is prevented. Filaments I5 and I1 capable of electronemission, which may be of the thoriated type or of the oxide-coatedtype, aresuitably secured to the terminals of each pair of leads II andI3 that project through the presses 1 and 9. The filaments I5 and I1 maybe suitably heated by current which is supplied through the leads II andI3 from a source of power (not shown).

The control electrode I9 comprises a cylindrical open structure disposedabout one filament I1 and its associated leads I 3 and suitablysupported by a plurality of rods 2| which are secured to a metalliccollar 23. The collar 23 is, inl turn, mounted on the stem 5 and issecured bya screw 21, which passes through openings in a plurality oflips 29 extending from the terminals of the collar, and engages a nut3|. The electromotive force that is applied to the control electrode I9is brought in through a lead 33 which is sealed to the press 5, and toone terminal 35 to which -a flexible wire 31V soldered to the collar 23,is secured.

The envelope I in which the electrodes are disposed may be suitablyevacuated before it is sealed off. It is well to remember that myinvention is applied in particular, to tubes in which a quantity of gasis disposed within the envelope. As is well known, the pressure of thegas within the envelope may vary from a few microns to severalcentimeters of mercury. The characteristic of the device is, of course,dependent on the pressure of the gas within the envelope and on thecharacter of the gas. However, it is apparent that as long as suiiicientgas forionization is present within the container, spurious conductivitywill takerplace between the elements of the principal electrodes I5 andI1 unlessr they are properly shielded from each other by the controlelectrode I9.

While my invention has particular applicability to gaseous electricdischarge devices, it should be kept in mind that in certain connectionsit may be applied even to high vacuum devices. Insofar as my inventiondoes apply to high vacuum devices, its scope should be extended toinclude such devices.

The apparatus of the type shown in Fig. 2 is in many respects similar tothe apparatus shown in Fig. 1. However, the device shown in this view ismore symmetric in its structure than the device shown in Fig. 1. Theprincipal elementof symmetry in the device is the control electrode 3.9which comprises an attenuated open-end cylinder equipped with a centralpartition 4I. 'I'he walls of the cylinder 39 are disposed adjacent tothe supports 4I IV and I3 of the laments I5 and I1 and the partition 4Iis disposed substantially midway between the two filaments. Thecylindrical control electrode 39 is supported from a collar 23, as isthe control electrode I9 of apparatus of the type shown in Fig. 1, andthe electromotive forceis supplied thereto through alead 33 sealed tothe press 9 and through a wire 31 lsoldered to the collar 23 and securedto -the internal end 35 of the lead 33'.

The energy for heating the filaments I5 and I1 is applied to the leadsII and I3 through a plurality of transformers 43 and 45 of' similarelectrical characteristic. The central taps 41 and 49 of the secondaries5I and 53 of the transform ers 43 and 45 whereby the power is appliedfor heating the filaments I5 and I1 are connected to each other througha suitable alternating power supply source (not shown) and through theload 55 which the system is to feed. A plurality of impedances 51 and 59of substantially similar characteristics are connected across thealternating source.

The control electrode 39 is connected to the junction of the impedances51 and 59 preferably through a suitable biasing battery 6I and throughthe secondaries 63 and 65 of a plurality of transformers 61 and 69whereby the potentials necessary for the control of the electricdischarge device are applied to the control electrode 39. One of thetransformers may be utilized for applying the suitable controllingpotential for the combination of one principal electrode and the controlelectrode, and the other transformer may be utilized for the control ofthe other combination of principal electrode and control electrode.

It is to be noted that for certain purposes a single transformer may beutilized for control.

However, if two transformers are utilized the electromotive forcesimpresed for controlling purposes should not be of the sinusoidal type,for in such a case a combined effect produced by the two transformerswill be a new effect such as trolling transformers 61 and 59 are suchthat the device conducts current from a predetermined point in each halfwave of voltage applied to the principal electrodes.

In such a case the secondaries 63 and 65 of the controlling transformers61 and 69, respectively, may have induced in them starting impulses ofsuitable character and at suitable intervals to yield the necessarypower. The current transmitted by the tube will, in such a case, becontrolled by the point in the half wave of the voltage applied to theprincipal electrodes I5 and I1 of the tube at which the impulse isapplied to the control electrode 39. The point may be shifted by somephase-shifting device which may be suitably associated with thecontrolling transformers.

The controlling transformers may be utilized to start and stop thecurrent transmitted by the principal electrodes I5 and I1 in suitablemanner. Thus, one transformer may provide a potential to the controlelectrode 39 for blocking the discharge in the tube while the other maybe utilized for applying a potential to the control electrode 39 tostart a discharge in the tube.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the G5 prior art and by the spirit of theappended claims.

I claim as my invention: 1. An electric discharge device comprising a.plurality of excitable electrodes forming the terminals of a dischargepath, means for supporting 2. A gaseous electric discharge devicecomprising a container a plurality of excitable electrodes forming theterminals of a discharge path disposed within said container, means forsupplying power to said electrodes and a perforated electrode completelyenclosing one of said excitable electrodes and the elements of saidpower supply means associated therewith that are disposed within saidcontainer and an electrical network having said excitable electrodes asthe terminals thereof.

3. A gaseous electric discharge device including a plurality ofelectrodes to be heated and to emit electrical charges when in heatedcondition and to form terminals of a discharge path, means forsupporting said electrodes and a control electrode comprising an openstructure completely enclosing one of said electrodes and saidsupporting means associated therewith and an electrical network havingsaid electrodes to be heated as the terminals thereof.

4. A gaseous electric discharge device including a container, aplurality of electrodes to be heated and to emit electrical charges whenin heated Y condition and to form the terminals of a discharge path,disposed within said container, means cooperating with said electrodesto supply the energy necessary for heating them and a control electrodecomprising an open structure completely enclosing one of said electrodesand the elements of said energy supply means associated therewith thatare disposed within said container and an electrical network having saidelectrodes to be heated as the terminals thereof.

5. In a gaseous conductor having electrical symmetry of the typeincluding a container having an ionizable medium enclosed therein, aplurality of emitters of electrical charges to ionize said medium, saidemitters being disposed to alternately receive charges of oppositepolarity, means for supplying power to said emitters and a controlelectrode comprising an open structure enclosing said emitters and theelements of said power supply means associated with said emitters thatare disposed within said container.

6. A three-electrode electric discharge device comprising a dischargepath, two incandescible main electrodes forming the terminals of thesaid discharge path and a control electrode extending across thedischarge space between, the two main electrodes.

7. An electric discharge device comprising a discharge path, a pluralityof substantially similar main electrodes, means for maintaining bothsaid electrodes in a state in which they emit electrical charges evenwhen they are at the same electrical potential, said main electrodesforming the terminals of the said discharge path, and a controlelectrode extending across the discharge path between said mainelectrodes, said main electrodes being symmetrical with respect to saidcontrol electrode.

8. In combination, an electric discharge device comprising a dischargepath, a plurality of electrodes adapted to emit electrical charges andof substantially similar structure and to form the terminals of the saiddischarge path and a control electrode intersecting substantially all ofthepaths of said charges from one of said electrodes to another and anetwork having electrical symmetry similarly associated with each ofsaid emitting electrodes, the electrical central elements of saidnetwork being connected with said control electrode. Y

9. An electrical discharge device comprising a container, a dischargepath in said container, a plurality of substantially similar mainelectrodes disposed in said container and forming the terminals of thesaid discharge path, means for maintaining both said electrodes in astate in which they emit electrical charges even when they are at thesame electrical potential, a single control electrode intersectingsubstantially all of the paths of said electrical charges from one mainelectrode to another main electrode.

STEPHAN P. SASHOFF.

